Combinational Logic Circuits Questions

• Implementing simplified SOP (sum-of-products) Which universal gate family allows simplified sum-of-products expressions to be realized directly using only that one gate type, generally with little or no increase in circuit complexity?
• HDL terminology clarity In hardware description languages (HDLs) such as Verilog or VHDL, what best describes the term 'literals' in the context of writing code and testbenches?
• Decoder sizing How many 3-line-to-8-line decoders are required to realize a 1-of-32 decoder (select exactly one output out of 32 lines), assuming any necessary small predecode or gating can be handled outside these decoder ICs?
• Boolean forms — identifying product-of-sums (POS) Which of the following Boolean expressions is written in canonical product-of-sums (sum terms multiplied together) form?
• Priority encoder 74HC147 — resolving multiple active inputs A 74HC147 has 10 active-LOW inputs (I0–I9) and 4 active-LOW outputs (Y3 Y2 Y1 Y0). If inputs 4 and 5 are both LOW (asserted) and all other inputs are HIGH, what is the state of the four outputs?
• Decoder used as a demultiplexer — control and data roles How can a standard decoder be used to implement a demultiplexer (DeMUX)? Choose the correct wiring approach.
• Decoding a specific binary word — logic required for 1101 Which combination of gates can be used to decode and assert only when the 4-bit input equals 1101 (MSB→LSB)?
• Troubleshooting a dead interconnect — best tool choice An output gate drives four input gates on different ICs. Power is present; the source gate shows a valid pulsing signal on the oscilloscope, but the interconnecting node shows no signal. Which instrument best helps isolate the open/short location along the PCB trace?
• Full-adder single-bit case — Cin = 0 For a full-adder with Cin = 0 and inputs A = 1, B = 1, what are the outputs for sum (∑) and carry-out (Cout)?
• 4-bit parallel adder — adding 1011 and 1111 with Cin = 1 Two 4-bit binary numbers (A = 1011 and B = 1111) are applied to a 4-bit parallel adder with carry-in Cin = 1. What are the resulting 4-bit sum (∑4∑3∑2∑1) and the carry-out (Cout)?
• Karnaugh map (K-map) grouping rules — which is invalid? In K-map simplification, which of the following cell combinations cannot be grouped as valid adjacencies to form implicants?
• Encoders — Cascading Two 8-to-3 Encoders If two 8-line-to-3-line encoders are combined to implement a 16-line-to-4-line encoder (using appropriate enable or cascading signals), how many output lines does the resulting encoder provide?
• Karnaugh Maps — Effect of Looping on Variables When grouping adjacent 1-cells on a K-map (looping), which variables are eliminated from the resulting simplified product term?
• Sum-of-Products (SOP) — Structural Advantage Which statement highlights a key practical advantage of expressing logic in sum-of-products (SOP) form for implementation with basic gates?
• VHDL Libraries — Meaning of Macrofunctions In the context of VHDL-based design flows and vendor libraries, macrofunctions are best described as which of the following?
• Hardware Design Flow — Next Step After Verification After a design engineer is satisfied through simulation and review that the logic will work, what is the typical next step in a programmable logic or ASIC prototyping workflow?
• BCD to Binary — Convert 0001 0010 0110 (BCD) to Pure Binary A BCD code of 0001 0010 0110 represents the decimal digits 1, 2, and 6. Convert this BCD value to its equivalent pure binary representation.
• Multiplexer Fundamentals — Select Lines vs. Inputs How many data select lines are required by a multiplexer to select exactly eight distinct inputs (one-hot to binary selection)?
• Sizing cascaded adders for required operand width How many 4-bit parallel adders must be cascaded to add two unsigned binary numbers when each number can represent decimal values up to 300 (base 10)?
• Troubleshooting erratic TTL behavior on a dense board You observe highly erratic, inconclusive logic readings at numerous ICs scattered across a TTL board with dozens of chips. Which single fault is most likely the root cause?